Hasegawa Hiroshi, Yamauchi Takeshi, Kraemer William J
Laboratory of Exercise Science, Department of Business Management, Ryukoku University, Kyoto, Japan.
J Strength Cond Res. 2007 Aug;21(3):888-93. doi: 10.1519/R-22096.1.
There are various recommendations by many coaches regarding foot landing techniques in distance running that are meant to improve running performance and prevent injuries. Several studies have investigated the kinematic and kinetic differences between rearfoot strike (RFS), midfoot strike (MFS), and forefoot strike (FFS) patterns at foot landing and their effects on running efficiency on a treadmill and over ground conditions. However, little is known about the actual condition of the foot strike pattern during an actual road race at the elite level of competition. The purpose of the present study was to document actual foot strike patterns during a half marathon in which elite international level runners, including Olympians, compete. Four hundred fifteen runners were filmed by 2 120-Hz video cameras in the height of 0.15 m placed at the 15.0-km point and obtained sagittal foot landing and taking off images for 283 runners. Rearfoot strike was observed in 74.9% of all analyzed runners, MFS in 23.7%, and FFS in 1.4%. The percentage of MFS was higher in the faster runners group, when all runners were ranked and divided into 50 runner groups at the 15.0-km point of the competition. In the top 50, which included up to the 69th place runner in actual order who passed the 15-km point at 45 minutes, 53 second (this speed represents 5.45 m x s(-1), or 15 minutes, 17 seconds per 5 km), RFS, MFS, and FFS were 62.0, 36.0, and 2.0%, respectively. Contact time (CT) clearly increased for the slower runners, or the placement order increased (r = 0.71, p < or = 0.05). The CT for RFS + FFS for every 50 runners group significantly increased with increase of the placement order. The CT for RFS was significantly longer than MFS + FFS (200.0 +/- 21.3 vs. 183.0 +/- 16 millisecond). Apparent inversion (INV) of the foot at the foot strike was observed in 42% of all runners. The percentage of INV for MFS was higher than for RFS and FFS (62.5, 32.0, and 50%, respectively). The CT with INV for MFS + FFS was significantly shorter than the CT with and without INV for RFS. Furthermore, the CT with INV was significantly shorter than push-off time without INV for RFS. The findings of this study indicate that foot strike patterns are related to running speed. The percentage of RFS increases with the decreasing of the running speed; conversely, the percentage of MFS increases as the running speed increases. A shorter contact time and a higher frequency of inversion at the foot contact might contribute to higher running economy.
许多教练针对长跑中的脚着地技术提出了各种建议,旨在提高跑步成绩并预防受伤。多项研究调查了后脚跟着地(RFS)、中脚着地(MFS)和前脚掌着地(FFS)模式在脚着地时的运动学和动力学差异,以及它们在跑步机和地面条件下对跑步效率的影响。然而,对于精英级别的实际公路赛中脚着地模式的实际情况却知之甚少。本研究的目的是记录在一场半程马拉松比赛中精英国际水平选手(包括奥运会选手)的实际脚着地模式。在15.0公里处,用2台120赫兹的摄像机从0.15米的高度对415名跑步者进行拍摄,获取了283名跑步者的矢状面脚着地和离地图像。在所有分析的跑步者中,74.9%观察到后脚跟着地,23.7%为中脚着地,1.4%为前脚掌着地。在比赛15.0公里处将所有跑步者按排名分成50个跑步者组时,速度较快的跑步者组中脚着地的百分比更高。在前50名中,包括实际排名第69位、在45分53秒通过15公里点的跑步者(此速度代表5.45米×秒⁻¹,即每5公里15分17秒),后脚跟着地、中脚着地和前脚掌着地的比例分别为62.0%、36.0%和2.0%。较慢的跑步者或排名顺序增加时,接触时间(CT)明显增加(r = 0.71,p≤0.05)。每50个跑步者组中后脚跟着地+前脚掌着地的接触时间随着排名顺序的增加而显著增加。后脚跟着地的接触时间明显长于中脚着地+前脚掌着地(200.0±21.3毫秒对183.0±16毫秒)。在所有跑步者中,42%的人在脚着地时观察到明显的足内翻(INV)。中脚着地的足内翻百分比高于后脚跟着地和前脚掌着地(分别为62.5%、32.0%和50%)。中脚着地+前脚掌着地伴有足内翻的接触时间明显短于后脚跟着地有或没有足内翻的接触时间。此外,伴有足内翻的接触时间明显短于后脚跟着地没有足内翻的蹬地时间。本研究结果表明,脚着地模式与跑步速度有关。后脚跟着地的百分比随着跑步速度的降低而增加;相反,中脚着地的百分比随着跑步速度的增加而增加。较短的接触时间和脚接触时较高的内翻频率可能有助于提高跑步经济性。